WHISK both flours, spices, baking soda and salt in a bowl.
BEAT butter and sugar in a large bowl with an electric mixer on medium, scraping sides and bottom of bowl, until fluffy, about 3 min. Beat in egg. Reduce speed to medium-low and beat in flour mixture until just combined.
TRANSFER dough to a surface and knead until smooth, about 15 times. Divide in half and wrap in plastic wrap. Flatten into discs and refrigerate until firm, 1 hr.
PREHEAT oven to 350F. Line 2 baking sheets with parchment.
ROLL dough on a lightly floured surface to a scant ¼-in. thickness. Cut out shapes using 2 ½-in. cookie cutter, rerolling scraps and refrigerating as needed. Place cookies on prepared sheet and chill for 15 min.
LIGHTLY brush dough with water and gently press almonds to adhere. Bake until edges are browned, 14 to 15 min. Let cool for 5 min, then transfer to a rack to cool. Repeat with remaining dough.
Nutrition (per cookie)
Kitchen Tip: Invest in a pastry brush with natural bristles to ensure even coating over speculaas cookies.